1. Something passed between routines or programs that enables the receiver to perform some operation; a capability ticket or opaque identifier . Especially used of small data objects that contain data encoded in a strange or intrinsically machine-dependent way. E.g. on non- Unix operating system s with a non-byte-stream model of files, the result of " ftell " may be a magic cookie rather than a byte offset; it can be passed to " fseek ", but not operated on in any meaningful way. The phrase "it hands you a magic cookie" means it returns a result whose contents are not defined but which can be passed back to the same or some other program later.
2. An in-band code for changing graphic rendition (e.g. inverse video or underlining) or performing other control functions. Some older terminals would leave a blank on the screen corresponding to mode-change magic cookies; this was also called a glitch (or occasionally a "turd"; compare mouse droppings ).
See also cookie .
[ Jargon File ]
(1995-01-25)